Isamu Kawabori

Incidence of exercise-induced asthma in children

The incidence of exercise-induced asthma (EIA) was studied in 134 asthmatic, 102 nonasthmatic atopic, and 56 nonatopic children. Pulmonary function tests measuring forced vital capacity (FVC) and one-second forced expiratory volume (FEV1) were performed on each child prior to and serially for 20 minutes following free running exercise. The incidence of the EIA among the asthmatic and atopic nonasthmatic children was 63% and 41% respectively, and 7% among control subjects. Airway function was studied prior to and after a standardized free running exercise test. Forty-one percent of the nonasthmatic and 63% ofthe asthmatic atopic children had a significant decrease in airway function as compared to 5% of the nonallergic subjects.

Noninvasive determination of pressure gradients in children: Two methods employing pulsed Doppler echocardiography

Pulsed Doppler echocardiography has been considered poorly suited for high velocity blood flow measurement, because of the problem of signal aliasing. Two methods for reduction of aliasing in a pulsed system were evaluated in an attempt to measure flow velocities characteristic of significant pressure gradients. With the angle correction method, carrier frequency, pulse repetition frequency and intercept angle were manipulated using a commercially available two-dimensional pulsed Doppler system. Forty children undergoing cardiac catheterization were studied. Gradients of 60 to 70 mm Hg were accurately predicted by this method, and gradients above 90 mm Hg were underestimated. Overall correlation (r) value was 0.95. The method is limited primarily by the introduction of potential error in measurement of intercept angle; it is advantageous in that it can be attempted using currently available pulsed Doppler echographic systems. With the multiple sample volume method, pulse repetition frequency was increased through the addition of extra sample volumes. Carrier frequency was minimized and angle correction was not employed. Thirty-nine children underwent cardiac catheterization using a prototype instrument. Excellent agreement between Doppler predictions and actual gradients was found for gradients up to 100 mm Hg (r = 0.99). Although this method requires new instrumentation, it is advantageous in that gradients are accurately predicted and cannot be overestimated. Both methods retain the advantages of pulsed Doppler study for comprehensive flow evaluation and reference their quantitative application within a two-dimensional echographic format. Neither method is simple, and each has been validated only in pediatric subjects.

Noninvasive estimation of peak pulmonary artery pressure by M-mode echocardiography

In an attempt to predict peak pulmonary artery pressure from routine M-mode echocardiographic tracings, 95 infants and children with congenital heart disease were examined. Following the Burstin method for prediction of peak pulmonary artery pressure, which was originally based on the phonocardiogram and jugular phlebogram, M-mode echocardiography was used to measure the interval from pulmonary valve closure to tricuspid valve opening, namely, the period of isovolumic diastole. The measured interval was plotted on a modified table relating the interval, heart rate and predicted peak pulmonary artery pressure. The peak pulmonary artery pressure predicted by echocardiography was compared with that measured at cardiac catheterization. The correlation between predieted and actual peak pulmonary artery pressure was good (r = 0.86) for routine studies with the patient in the nonsedated state. All patients with a predicted peak pressure less than 40 mm Hg were found at catheterization to have a pressure less than 40 mm Hg. The correlation was better (r = 0.96) when comparing predictions made from the echocardiogram obtained while the patient was sedated for catheterization. Prediction of the magnitude of elevation of peak pressure was especially good when prediction and measurement were nearly simultaneous. Predictions were less accurate in the presence of tachycardia at rates of more than 155 beats/min. The method for estimating peak pulmonary artery pressure from M-mode echocardiographic tracings is reliable, relatively simple and clinically useful.

Pulsed Doppler echocardiographic detection of total anomalous pulmonary venous return: resolution of left atrial line.

During precatheterization M mode echocardiographic examination, 33 infants were identified as having findings including right ventricular enlargement and presence of a line within the left atrial portion of the M mode tracing suggesting the possibility of cor triatiatum or total anomalous pulmonary venous return. Pulsed Doppler echocardiography was used to sample blood characteristics on either side of the left atrial line to determine which line was artifactual and which was indicative of an important structure. Five patients whose blood flow characteristics were different on either side of the left atrial line were subsequently proved to have total anomalous pulmonary venous return at cardiac catheterization. In the remaining infants blood flow characteristics were identical on either side of the line, and catheterization excluded total anomalous pulmonary venous return and cor triatriatum. In all patients who had total anomalous pulmonary venous return, drainage involved a persistent left superior vena cava, and this vascular structure was identified by pulsed Doppler examination from the suprasternal notch. Pulsed Doppler echocardiography appears to be a useful technique for resolution of left atrial lines found on M mode echocardiography.

Noninvasive evaluation of Blalock-Taussig shunts: determination of patency and differentiation from patent ductus arteriosus by doppler echocardiography.

Pulsed Doppler echocardiography has been used to detect continuous turbulent flow in the right pulmonary artery after Blalock-Taussig shunts. Since continuous turbulent flow could also arise from patent ductus arteriosus (frequently present in the neonate), continuous turbulent flow in the right pulmonary artery is not specific for Blalock-Taussig shunt function. We evaluated 35 Blalock-Taussig shunts from suprasternal or high parasternal approach for flow in the right pulmonary artery, and in the Blalock-Taussig shunts themselves. From precordial approach, Doppler evaluations of the main pulmonary artery were also made in search of flow characteristic of patent ductus arteriosus. Doppler detection of flow within the Blalock-Taussig shunts indicated shunt patency, and indicated that continuous turbulent flow in the right pulmonary artery was not due to only patent ductus arteriosus. Shunts were proven patent in 31 patients, occluded in four. Twelve patients also had patent ductus arteriosus. By Doppler, the right pulmonary artery had continuous turbulent flow in 30 of 31 patients in whom the right pulmonary artery was found. From the suprasternal or high parasternal approach, the right Blalock-Taussig shunts were detected by marked continuous turbulent flow directed away from the transducer, between the aortic and superior vena caval flow signals. Left Blalock-Taussig shunts had similar directional continuous turbulent flow. Prosthetic shunts were identified by the dense shunt material. Twenty-four of 31 functional shunts were identified, and all contained continuous turbulent flow. Three left-sided shunts were missed. All four occluded shunts were identified by Doppler, and had no lumen flow within.(ABSTRACT TRUNCATED AT 250 WORDS)

Need for an Improved Standard for Blood Pressure Cuff Size The Size Should Be Related to the Diameter of the Arm

* From the Section of Pediatric Cardiology, University of Kansas Medical Center, Kansas City, Kans. 66103. ** From the Division of Pediatric Cardiology, Department of Pediatrics, University of Washington School of Medicine, Seattle, Wash. 98195. Assisted by a grant from the U.S. Public Health Service, Number HL-13517. Correspondence to Warren G. Guntheroth, M.D., Department of Pediatrics (RD-20), University of Washington School of Medicine, Seattle, Wash. 98195. A SIGNIFICANT ERROR in arterial blood pressure readings can result from improper selection or application of the sphygmomanometer cLiff.1 One common source of error in children is improper cuff size. Most pediatric references2-6 recommend that the cuff cover two-thirds of the length of the upper arm. With adults, The American Heart Association7 has recommended that the

A Twenty-Month Experience Comparing Conventional Pulsed-Doppler Echocardiography and Color-Coded Digital Multigate Doppler, for Detection of Atrioventricular Valve Regurgitation, and Its Severity

Conventional pulsed-Doppler echocardiographic (PDE) detection of mitral regurgitation has been shown in several series to have a sensitivity and specificity of about 90%, when compared with angiocardiography [1, 2, 3]. We, and others have used PDE for detection of tricuspid valve regurgitation as well [4, 5, 6]. In many centers, including ours, atrioventricular valve regurgitation (AVVR) has been detected through the use of an audio PDE output, with detection of a harsh systolic flow disturbance posterior to the atrioventricular (AV) valve. Though it is not difficult to differentiate smooth, normal flow from rough, disturbed flow on the basis of the audio signal, some remain skeptical about this subjective differentiation. A time interval histographic (TIH) output is commonly used for PDE registration, depicting abnormal flow with dot scatter, and documenting normal flow with the absence of dot scatter. While several centers have enjoyed good sensitivity and specificity for PDE diagnosis of various flow disturbances, even with the several limitations imposed by audio and TIH outputs, there is need for a PDE display format which does not require adjustment during examinations, and which does not have the potential for subjectivity. A 128-channel, digital multigate Doppler (DMD) device, described by Brandestini et al. [7], has the distinct advantage of visual representation of flow, superimposed on a familiar M-mode format. For the question of AVVR, the display format either shows regurgitant flow posterior to the AV valve, or shows no regurgitant flow. The detection and display of the flow characteristics are not under the control or adjustment of the examiner; the only judgement made in the evaluation is the presence or absence of directional flow.

Pulsed doppler echocardiographic evaluation of the cyanotic newborn: Identification of the pulmonary artery in transposition of the great arteries

Abstract During M mode echocardiographic evaluation of cyanotic newborn infants, one may find two ventricles and two great vessels, but not have proof of their identity. Identification of the great vessels is important in evaluation of possible transposition of the great arteries. In a series of 68 cyanotic neonates pulsed Doppler echocardtography was applied to test the hypotheses that (1) a patent ductus arterlosus in present in most cyanotic neonates, (2) the great vessel that receives diastolic ductal flow is the pulmonary artery, and (3) specific noninvasive identification of pulmonary artery will allow diagnosis or exclusion of transposition of the great arteries. On M mode examination, the relations of the great vessels were normal in 43 infants; in all, pulsed Doppler echocardiography detected a patent ductus arteriosus flowing into a normally positioned pulmonary artery. The cyanosis in these 43 patients was later proved to be of pulmonary origin. In eight infants, the relation of the great vessels suggested transposition, and in all eight, Doppler echocardiography detected a patent ductus flowing into the posterior great vessel, proved at angiocardiography to be the transposed pulmonary artery. In 17 patients, the relation of the great vessels was front to back, neither “normal” nor suggestive of classic d transposition. A patent ductus arterlosus, detected with pulsed Doppler echocardiography in all 17, flowed into the anterior great vessel in the 14 normal infants, and flowed into the transposed pulmonary artery in the 3 with proved transposition. It is concluded that ductal patency is prevalent in cyanotic neonates, and that pulsed Doppler echocardiographic detection of ductal flow can define the pulmonary artery; such definition is most helpful in resolving the question of transposition in infants with a relation of the great vessels that is neither normal nor suggestive of transposition.

Doppler Pressure Gradient Estimation in Children Accuracy, Effect of Activity and Exercise, and the Need for Sedation during Examination

ABSTRACT. Noninvasive estimation of pressure drop has been shown to be an accurate and useful application of Doppler echocardiography. Most accuracy series have used patient‐sedated catherization gradient measurements as the standard of reference. Doppler gradient estimates, however, are commonly made without sedation of the patient when hemodynamics may differ from those present at catheterization. We questioned whether (1) “unsedated” Doppler gradient estimates would correlate in a useful way with “sedated” catheter measurements, (2) Doppler gradient estimates would vary with patient activity, exercise or crying, and (3) Doppler gradient estimates made using chloral hydrate sedation would prove useful in predicting sedated catheter measurements. Twenty‐five infants and children were examined under conditions 1 and 2 above, and 20 under condition 3. Sedated Doppler estimates, performed at the time of catheterization corresponded closely with catheter measurements (r=0.97, SEE=4.8), confirming the accuracy of the Doppler method. Gradients estimated by Doppler without sedation, or with activity, correlated poorly with sedated catheter measurements (SEE=16.2, SEE=34.9, respectively). Use of chloral hydrate sedation for Doppler estimates resulted in good correlation with subsequent sedated catheter measurements. The results demonstrate marked increases in noninvasive Doppler pressure gradient estimates under conditions other than sedation. Clinicians tend to think in terms of sedated catheter‐gradients as the standard of reference for evaluation of severity and need for surgery. Ultrasonic data can only be used if Doppler estimates are performed under similar physiologic conditions; in children this requires sedation.

Potentially Serious Drug Interactions Secondary to High-Dose Diltiazem Used in the Treatment of Pulmonary Hypertension

Two patients had potentially serious drug interactions (phenytoin, digoxin) that were probably attributable to changes in pharmacokinetics and pharmacodynamics caused by high‐dose calcium channel blocker therapy (diltiazem) in the treatment of pulmonary hypertension. Even in the approved normal dosages for the treatment of angina and hypertension, calcium channel blockers are known to cause significant changes in the metabolism of other drugs. Currently, no data exist on the effects of the very high dosages of these drugs, administered to patients with pulmonary hypertension, on the metabolism and clearance of other agents, although, based on our experience and literature reports, recommendations for monitoring therapy can be made.